Detection systems for the railroad industry provide methods and apparatus for detecting dragging, or otherwise improperly hanging or protruding vehicle equipment when a train passes by a railside monitoring station. Systems or apparatus for detecting the presence of objects dragging beneath a train are sometimes referred to as “draggers”. In various implementations, draggers may be placed at twenty mile intervals, ten mile intervals, or other spaced intervals along stretches of railroad track, in addition to being placed at railroad crossings and in railroad switching yards. If a dragging object, or otherwise improperly protruding equipment is detected by a dragger, the train may be stopped so that the object can be secured, or removed to reduce the potential for derailment or other problems. Existing systems for detecting dragging equipment underneath trains include sensors mounted on stationary strike plates or impact elements positioned in the path of the protruding equipment. Impacts of protruding equipment against the stationary impact elements cause vibrations or accelerations in the impact elements, and in the sensors mounted thereon.
One problem associated with these types of impact detection systems involves the triggering of false alarms, in particular, false alarms can be triggered by vibrations from flat wheels. A flat wheel, or a wheel with worn tread can cause a vertical impact on existing impact sensors that the existing impact detection systems are not capable of distinguishing from actual dragging equipment.
One attempt to avoid the problem of triggering false alarms is disclosed in U.S. Pat. No. 6,412,332 to M. Bartonek that issued on Jul. 2, 2002 (the '332 patent). The '332 patent discloses an apparatus for detecting objects dragging beneath a train as the train travels along a rail. The apparatus includes a stationary impact element rigidly supported along the rail, with a single axis sensor disposed in a horizontal orientation relative to the impact element to detect only horizontal components of any impact forces.
Although the impact detection system of the '332 patent eliminates detection of vertical forces, and therefore reduces the detection of vibrations from flat wheels, this solution for selective detection of only impacts that create horizontal forces, may provide a less than optimal impact detection system. In particular, the impact detection system of the '332 patent has no way to detect impacts of dragging equipment that create only vertical forces.
The disclosed dragging equipment detector is directed to overcoming one or more of the problems set forth above and/or other problems in the art.